Optical recording medium having read-only storage area and writeable storage area and recording/reproducing apparatus and method therefor

ABSTRACT

An optical recording medium having a read-only storage area and a writable storage area and a recording/reproducing apparatus and method therefor. The optical recording medium is a hybrid disc having both the read-only storage area, which is suitable for mass production of information having the same contents, and the writable storage area on which data can be recorded, updated or added at a user&#39;s option. The read-only storage area has a structure that is completely compatible with a digital versatile disc read only memory (DVD-ROM) specification, and the writable storage area is compatible with the recording/reproducing characteristics of a writable DVD specification so that an existing reproducing-only apparatus can read information from the read-only storage area, and data can be recorded in the writable storage area using an apparatus obtained by minimally changing an existing recording/reproducing apparatus while maintaining the physical recording characteristics of the existing recording/reproducing apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/656,709filed Sep. 7, 2000 and claims the benefit of U.S. ProvisionalApplication No. 60/214,734, filed Jun. 29, 2000, in the U.S. Patent &Trademark Office, the disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium having a read-onlystorage area and a writable storage area and a recording/reproducingapparatus and method therefor, and more particularly, to a recordingmedium having a read-only storage area complying with a digitalversatile disc (DVD) specification and a writable storage areaphysically compatible with a DVD-writable specification and arecording/reproducing apparatus therefor.

2. Description of the Related Art

Generally, read-only optical recording media that are manufactured byinjection molding have characteristics in that information is configuredin the form of embossments referred to as pits so that user informationis recorded on a mold, and the information is transferred duringinjection. Accordingly, read-only optical recording media areadvantageous in increasing production efficiency compared to the casewhere information is recorded on a floppy disc or a magnetic recordingmedium and distributed.

However, read-only optical recording media on which users cannot recorddata have a problem in that data cannot be modified or added inapplication examples such as an encyclopedia and popular music data foraccompaniment which frequently require modification of data and additionof data.

Meanwhile, among digital versatile disc specifications, read-only discsare defined in a digital versatile disc read only memory (DVD-ROM)specification (DVD Specification for read-only memory Part 1 version1.0). Discs on which a user can record data are defined in a digitalversatile disc random access memory (DVD-RAM) specification (DVDSpecification for rewritable memory Part 1), in a digital versatile discrecordable memory (DVD-R) specification (DVD Specification forrecordable memory Part 1), and in a digital versatile disc rewritablememory (DVD-RW) specification (DVD Specification for re-recordablememory Part 1).

However, discs having both a read-only specification and a recordablespecification are not defined so that requirements for modification ofdata and addition of data, which are characteristics of a recordabledisc, and requirements for mass copying of the same data, which is acharacteristic of a read-only disc, cannot be simultaneously satisfied.

When proposing a new optical disc satisfying the above requirements,compatibility with a recording/reproducing apparatus according to aconventional specification should be considered. In other words, it isimportant to make a new optical disc satisfying the above requirementsto be compatible with a conventional recording/reproducing apparatuswhich is made and performs, without consideration of a medium having thecharacteristics of both a recordable disc and a read-only disc.

In this case, it is apparent that complete compatibility cannot beachieved because the characteristic of a particular area on a singledisc changes. Accordingly, as for compatibility, the characteristics ofa read-only medium are primarily considered such that data in aread-only storage area can be reproduced in a conventional apparatus foronly reproducing, and simultaneously, a writable storage area isconsidered to be compatible with physical recording/reproducingcharacteristics defined in a conventional rewritable specificationtaking into account the fact that data can be additionally recorded orupdated in the writable storage area while a user is using a disc.

In addition, it is preferable that an optical recording medium having aread-only storage area and a writable storage area has drivecompatibility with a conventional DVD-ROM drive and a conventionalDVD-RAM drive.

For a clear understanding of the present invention, a structure of anoptical disc (optical recording medium) defined according to a digitalversatile disc read only memory (DVD-ROM) specification will bedescribed in detail. FIG. 1 is a sectional view of a conventional duallayer optical disc 10 defined according to the DVD-ROM specification.The optical disc 10 defined according to the DVD-ROM specificationcomprises first and second substrates 12, 14. Information layers 16, 18are formed on the first and second substrates 12, 14, respectively, andthe first and second substrates 12, 14 are united such that theinformation layers 16, 18 face each other. The information layer (16 inthis instance) nearer to a substrate on which a read laser beam isincident is defined as a first recording layer, and the underlyinginformation layer (18 in this instance) is defined as a second recordinglayer.

Such an optical disc 10 includes a lead-in area (not show) at aninnermost part of the optical disc 10 and a lead-out area (not shown) atan outermost part of the optical disc 10, or a middle area in whichvarious control information (not shown) and information on the physicalcharacteristics of the optical disc 10 is recorded, so that data in theinner part and the outer part can be steadily read.

Generally, a read-only optical disc is molded by injecting apolycarbonate resin material into a die, referred to as a stamper, onwhich information is formed in the form of embossed pits, such that theinformation can be transferred to the read-only disc. After forming theread-only optical disc by injection, a material such as aluminum havinga characteristic of reflecting light is sputtered on an informationsurface to form a reflective layer.

A DVD-ROM (the optical disc 10) is formed by uniting two discs (thefirst and second substrates 12, 14), each of which is molded accordingto the above method to have a thickness of 0.6 mm, so as to have a totalDVD-ROM thickness of 1.2 mm. One substrate may not have a recordinglayer, or each substrate may have two recording layers. In the casewhere each of first and second substrates 12, 14 has a single recordinglayer, when the optical disc is formed such that data can be read fromonly one side of the optical disc, the optical disc is referred to as adual layer optical disc. When a disc is formed such that data can beread from layers on both sides of the optical disc 10, the optical disc10 is referred to as a double sided disc.

As described above, since information is recorded on a read-only opticaldisc while it is being formed by injecting a polycarbonate resinmaterial into a stamper on which information is formed, the informationcan be formed on the read-only optical disc in a short time as comparedto a magnetic recording medium or a writable recording medium.Accordingly, the read-only optical disc is suitable for mass producingthe same data, such as a film or a computer game which needs to becopied in large quantity.

FIG. 2 is a diagram showing a structure of a conventional optical discrecording medium 20 having two data storage areas having differentcharacteristics. Data which can be reproduced using a laser of 780 nm isrecorded in a first recording area 26 on the optical disc 20, and datawhich can be reproduced using a laser of 635-650 nm is recorded in asecond recording area 27. Referenced numeral 22 denotes a standarddensity information layer for a compact disc (CD), reference numeral 23denotes a high-density information layer for a DVD, reference numeral 24denotes a second substrate layer, reference numeral 25 denotes a firstsubstrate layer, reference numeral 26 denotes the first recording areawhich is readable using the laser of 780 nm, and reference numeral 27denotes the second recording area which is readable using the laser of635-650 nm. The dual layer high-density optical disc 20 of FIG. 2 isdisclosed in U.S. Pat. No. 5,732,065, entitled “Optical InformationCarrier Including Standard and High Density Layers,” and filed on Sep.4, 1996.

FIG. 3 shows a structure of a complex recording layer 32 of a typicalwritable, optical recording medium 30. Since user data is not recordedon a disc during manufacturing of a writable medium such as a digitalversatile disc random access memory (DVD-RAM), substrates can be formedusing the same stampers. Unlike a read-only medium in which a reflectivelayer is simply formed, a complex recording layer including a pluralityof films (i.e., a dielectric layer 34, a recording layer 36, anotherdielectric layer 38 and a reflective layer 40 shown in FIG. 3) needs tobe formed on a substrate 42 to allow a user to record data on theoptical recording medium 30. A DVD-RAM or a digital versatiledisc-rewritable (DVD-RW) has a complex recording layer having amulti-layered structure such that recording can be achieved using achange in a material of the recording layer 36, that is, a changebetween an amorphous state and a crystalline state.

SUMMARY OF THE INVENTION

To solve the above and other problems, a first object of the presentinvention is to provide an optical recording medium that is compatiblewith a digital versatile disc (DVD) specification and also has aread-only storage area and a writable storage area.

A second object of the present invention is to provide an opticalrecording medium which has a read-only storage area and a writablestorage area, and on which control information for the writable storagearea is recorded in the read-only storage area so that the opticalrecording medium can be compatible with a DVD specification.

A third object of the present invention is to provide arecording/reproducing apparatus for an optical recording medium that iscompatible with a DVD specification and also has a read-only storagearea and a writable storage area.

In order to achieve at least the first and second objects, the presentinvention provides an optical recording medium comprising a substrate; aread-only storage area at an inner part of the substrate; and a writablestorage area at an outer part of the substrate.

To achieve at least the third object of the present invention, there isprovided an apparatus for recording/reproducing data onto/from anoptical recording medium having a read-only storage area at an innerpart of a substrate and a writable storage area at an outer part of thesubstrate, the apparatus comprising a system controller which generatesidentification information for indicating that the optical recordingmedium is a hybrid disc having the read-only storage area and thewritable storage area; and a recording unit which records the data ofthe read-only storage area, which is updated for use by correction,modification and addition, in the writable storage area, and thegenerated identification information in the lead-in area of theread-only storage area.

Preferably, the recording/reproducing apparatus further comprises areproducing unit which reproduces data from the optical recording mediumby controlling a reference linear velocity for reproduction at theread-only storage area to be the same as a reference linear velocity atthe innermost part of the writable storage area.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention willbecome more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a sectional view of an optical recording medium compatiblewith a conventional digital versatile disc read only memory (DVD-ROM)specification;

FIG. 2 is a diagram showing a structure of a conventional opticalrecording having two kinds of data storage areas having differentcharacteristics;

FIG. 3 is a diagram showing a structure of a conventional recordinglayer of a writable optical recording medium, which provides for a clearunderstanding of the present invention;

FIGS. 4 through 9 are examples of structures of embodiments of anoptical recording medium having a read-only storage area and a writablestorage area according to the present invention;

FIG. 10 is a diagram showing a control information format in a lead-inarea on an optical recording medium according to the present invention;

FIG. 11 is a diagram showing a structure of hybrid disc identificationinformation of the control information shown in FIG. 10;

FIGS. 12A and 12B are diagrams showing an information structure of alead-in area on an optical recording medium having a writablespecification and an information structure of a lead-in area on anoptical recording medium having a read-only specification, respectively,for clear understanding of the present invention; and

FIG. 13 is a block diagram of a recording/reproducing apparatus using anoptical recording medium according to embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now made in detail to the present preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings, wherein like reference numerals refer to the likeelements throughout. The embodiments are described below in order toexplain the present invention by referring to the figures.

When an optical recording medium (hereinafter, referred to as a hybriddisc) having both a read-only storage area and a writable storage area,which are defined in a DVD specification, is defined under the situationthat conventionally, individual DVD specifications for a read-onlymedium and a writable medium exist, compatibility of the specificationfor the hybrid disc with the conventional specifications becomes aproblem as described before. The term “writable” may indicate“recordable” for a DVD-R, “rewritable” for a DVD-RAM and “re-recordable”for a DVD-RW.

A recording medium having a ROM and a RAM area is mainly used forsupplying the same content in bulk by taking advantage of easyduplication, which is the characteristic of a read-only medium.Accordingly, the read-only storage area needs to be primarily consideredin solving a compatibility problem.

In addition, since a physical space on a disc is divided such that aspecific space is assigned as a read-only storage area, and anotherspecific space is assigned as a writable storage area, the physicalcharacteristics of a space on a hybrid disc are different from those ofa space on a disc having only one kind of storage area. Accordingly, itis apparent that the specification for the hybrid disc cannot becompletely compatible with conventional specifications.

In this specification, as for the compatibility, it is preferable thatthe read-only storage area has a compatibility such that data in theread-only storage area can be reproduced in a conventional reproducingapparatus, and a writable storage area is compatible with therecording/reproducing characteristics of a conventional writable mediumsuch that additional circuits necessary for implementing arecording/reproducing apparatus for recording, modifying or reproducingdata on the writable storage area can be minimized. By doing this, userdata stored in the read-only storage area can be reproduced in aconventional reproducing apparatus at least so that the hybrid disc canbe used for the same usage as that of a conventional DVD-ROM. Inaddition, a recording/reproducing apparatus for the hybrid discaccording to the present invention can modify data stored in theread-only storage area or add new data to the data stored in theread-only storage area, thereby securing compatibility of the hybriddisc with a conventional DVD reproducing apparatus.

A first embodiment which considers the requirements for suchcompatibility is shown in FIG. 4. In this diagram, a portion of a hybriddisc 40 is shown, wherein a data area 42, in which user data can beprerecorded according to a conventional DVD-ROM specification, has astart diameter of 48 mm indicating the beginning of the data area and amaximum diameter of 116 mm (in the case of a disc having a diameter of120 mm) or 76 mm ( in the case of a disc having a diameter of 80 mm). Inother words, the start diameter is predetermined, but the end diameterof the data area is not fixed to a certain value. A range is given forthe end diameter.

Accordingly, the start diameter of the data area is set to 48 mm, andthe end diameter of the data area is set to be larger than 48 mm andsmaller than 116 mm in the case of an optical disc having a diameter of120 nm (or 76 mm in the case of an optical disc having a diameter of 80mm), and a writable storage area is defined in the remaining area otherthan an information area for recording control information among thearea in which read-only data is not recorded, thereby obtaining optimalcompatibility with a conventional DVD-ROM.

When considering the fact that a recording area is divided into aplurality of zones using a zoned continuous linear velocity (ZCLV)method in a DVD-RAM, it is preferable to assign at least an areacorresponding to the size of a single zone defined in a DVD-RAMspecification for the writable storage area.

In the case of the conventional DVD-RAM, various control information,such as the rotation speed of a disc and defect management information,are closely related to the size and the location of a zone. Inparticular, the rotation speed of the DVD-RAM is not only connected witha zone but also closely related to the recording characteristics of sucha phase-change recording medium. Accordingly, to be compatible with thephysical recording characteristics of the conventional DVD-RAM, it ispreferable to consider size and location in the assignment of zones whenthe read-only storage area and the writable storage area are defined onthe hybrid disc of the present invention.

In addition, the conventional DVD-ROM specification defines a dual layerdisc. Accordingly, it is preferable to dispose the read-only storagearea 44 defined by the dual layer DVD-ROM specification in an inner partof the hybrid disc 40 and the writable storage area of a single layerstructure 50 in an outer part of the hybrid disc 40 beyond the read-onlystorage area 44 on the hybrid disc, as shown in FIG. 4.

Since the conventional specification for the writable storage area 50defines only the single layer structure, it is preferable to dispose thewritable storage area 50 on a first recording layer 46, LAYER 0, on afirst substrate 52. This is because a heat transfer characteristicchanges, and this may result in a change in a recording characteristicin a writable medium including a recording layer having a multi-layerstructure when the order of a substrate on which the recording layer isformed and a plurality of layers included in the recording layer,changes in view of an incident laser beam.

The structure of the hybrid disc 40 shown in FIG. 4 defines a dual layerread-only storage area 44, thereby realizing a capacity of 4.7 Gbytes,which is the size of the most widely used DVD-ROM, by applying the duallayer read-only storage area 44, while including the writable storagearea 50.

FIG. 5 illustrates a second embodiment of the optical recording mediumaccording to the present invention wherein a hybrid disc 60 is shown. Afirst substrate 62 has a transparent area 66 without having any storagearea at its inner part and the writable storage area 50 at the outercircumference thereof. Meanwhile, the second substrate 54 has therecording layer 48, LAYER 1, in a read-only storage area 64 at its innerpart, which is spatially separated from the writable storage area 50 ofthe first substrate 62.

The two optical recording media, i.e., the second substrate 54 havingthe read-only storage area 64, and the first substrate 62 having thewritable storage area 50, are combined with each other, thereby formingan optical recording medium 60 having both the read-only storage area 64and the writable storage area 50. As for the present embodiment of theoptical recording medium, a writable medium manufacturing process and aread only medium manufacturing process can be applied separately, anddifferent stampers (not shown) can be used in manufacturing the secondsubstrate 64 having the read-only storage area 64 and the firstsubstrate 62 having the writable storage area 50. For this reason, evenif the content of data to be written onto the read-only storage area 64is changed, there is no need to change the stamper for the writablemedium (the first substrate 62). On the other hand, an advantage in viewof the read only medium, is that it is unnecessary to form a recordinglayer.

Also, the hybrid disc 60 as shown in the second embodiment in FIG. 5enables a read only disc manufacturer to produce a recording mediumhaving a writable storage area and a read-only storage area by simplycombining a medium having a writable storage area, which is commerciallyavailable, with a medium having a read-only storage area produced by themanufacturer.

FIG. 6 illustrates a third embodiment of the optical recording mediumaccording to the present invention, wherein a hybrid disc 70 is shown.The hybrid disc 70 has a single read-only storage area 74 at its innerpart and a writable storage area 50 at its outer part. Thus, the hybriddisc 70 having the read-only storage area 74 and the writable storagearea 50, which have different features, can be implemented with a singlesubstrate, which is a first substrate 52.

To avoid the read-only storage area 74 from being exposed during theformation of a recording layer 76 in a writable storage area 60, theread-only storage area 74 is covered with a mask (not shown) duringformation of the recording layer 76 in the writable storage area 50, andthe mask is removed before formation of an outermost reflective layer(not shown) of the hybrid disc 70, so that the hybrid disc 70 can beconstructed. A second substrate 84 has a dummy recording layer 58 inboth the read-only storage area 74 and the writable storage area 50, sothat no data is recorded on the entire dummy recording layer 58 Thehybrid disc having both a read-only storage area and a writable storagearea 50 can be produced through such successive processes using a singlestamper.

FIG. 7 illustrates a fourth embodiment of the optical recording mediumaccording to the present invention, showing a hybrid disc 90, in which adual layered read-only storage area 92 is formed at the inner part ofeach of the first and second substrates 102 and 104 by a two photopolymerization (2P) technique, and a writable storage area 100 adoptinga DVD-RAM format and having the recording/reproducing characteristicsdefined by a DVD-RAM format, is formed at the outer part of each of thefirst and second substrates 102 and 104. For this case, writing orreading data onto or from the first and second recording layers 106 and108, LAYER 0 and LAYER 1, formed at the first substrate 102 is performedthrough an incident side of entrance on the hybrid disc 90 of a laserbeam of the first substrate 102. Also, writing or reading data onto orfrom the first and second recording layers 106 and 108, LAYER 0 andLAYER 1, formed at the second substrate 104 is performed through anincident side of entrance on the hybrid disc 90 of a laser beam of thesecond substrate 104. In the hybrid disc 90 having such a structure,formation of the recording layer at a portion of the storage area may beomitted. For example, the first substrate 102 may have a single layeredread-only storage area or the second substrate may have no writablestorage area.

FIG. 8 illustrates a fifth embodiment of the optical recording mediumaccording to the present invention, wherein a hybrid disc 110 is shown.The structure of the hybrid disc 110 is the same as that shown in FIG.4, except that the writable storage area 120 is formed with a duallayered structure (the writable storage area 120 of the first and secondrecording layers 46 and 48), and is arranged at the outer part of eachof the first and second substrates 52 and 114. As shown in FIG. 8,writing and reading operations are performed through the incident sideof the first substrate 52. For this case, recording/reproducingcharacteristics in the dual layered structure are different from thoseof the writable storage area having a single layered structure, so thatthe structure of a recording/reproducing apparatus for the opticalrecording medium may be complicated. Meanwhile, such a dual layeredstructure is advantageous due to an increased data writing capacity inthe writable area.

FIG. 9 illustrates a sixth embodiment of the optical recording mediumaccording to the present invention showing a hybrid disc 130, in which aread-only storage area 134 is formed over a first substrate 142, and awritable storage area 150 is formed over a second substrate 144. Theread-only storage area is formed of a first recording layer 146, LAYER0, and the writable storage area is formed of a second recording layer148. This configuration may lower the compatibility in readingoperations with other recording media. In addition, the recordingcharacteristics are changed and thus the compatibility in writingoperations with other recording media may be lowered. Advantages of thehybrid disc 130 shown in FIG. 10 are that a writable medium and a readonly medium can be separately manufactured, as described previously, anddata writing capacity increases.

In the case where the writable storage area 150 is formed at the secondsubstrate 144 and the read-only storage area 134 is formed at the firstsubstrate 142, the hybrid disc 130 can be constructed to enable readingor writing of data from or to two recording layers through the incidentside of the first substrate 142, rather than one side of the hybrid disc130 for one layer and the other side of the hybrid disc 130 for theother layer.

On the other hand, when the writable storage area 150 is formed at thefirst substrate 142, the second recording layer 148 must be formed of asemi-transmissive layer, and data from the read-only storage area 134formed at the second substrate 144 must be reproduced with a higher readpower so as to compensate for reduced read laser power due to the firstrecording layer 146 of the first substrate 142. For this case, it isvery likely that data of the first recording layer 146 will be erased orchanged by interference. The configuration shown in FIG. 9 contributesto minimizing such a problem with an increased writable storage area.

FIG. 10 illustrates the control information for correct playback fromthe optical recording medium according to the first through fifthembodiments of the present invention by a recording/reproducingapparatus.

As for a hybrid disc medium having a read-only storage area and awritable storage area, as previously mentioned, the read-only storagearea is constructed to have compatibility with a conventional DVD-ROMreproducing apparatus. For this case, there is no problem in using aconventional DVD reproducing apparatus. However, a disc identifier foruse in distinguishing a hybrid disc from a conventional DVD-ROM isrequired to enable an apparatus for recording/reproducing data onto/fromthe writable storage area to identify the hybrid disc. The need for suchidentification information may be satisfied by adding particularinformation to the lead-in area.

To implement the compatibility with a DVD reproducing apparatus which isable to recognize only a conventional DVD-ROM, it is preferable thatdata writing is performed with reserved bytes, without using thephysical format information of the control data zone. This is becausemodifying the physical format information, for example, the BP0, of theexisting control data zone including book type information indicatingthe type of specification book, and part version information of thespecification book, to be suitable for a new medium, may result inlosing compatibility.

In particular, DVD-ROMs do not utilize the 17^(th) through 32^(nd) bytesof the physical format information, and thus hybrid disc identificationinformation indicating a hybrid disc having a read-only storage area anda writable storage area can be written using some reserved bytes forother writing formats. As shown in FIG. 11, such hybrid discidentification information includes information on the presence orabsence of the writable storage area, which is an indicator of thehybrid disc, and on part version for the hybrid disc.

Comparing the lead-in information of a DVD-ROM with the lead-ininformation of a DVD-RAM that is a writable medium, the lead-ininformation of the writable medium contains all fields of the lead-ininformation of the DVD-ROM. On the other hand, the lead-in informationof the DVD-ROM uses only 16 bytes and the remaining bytes are reserved.

As for the writable medium, a plurality of information areas areallocated to the lead-in information for adding information on, forexample, the recording characteristics of the medium. Also, therecording density belonging to the lead-in information of the DVD-RAM isconstructed to be different from that of a DVD-ROM disc.

As shown in FIG. 10, when reproduction is carried out from the lead-inarea of the read-only storage area, the data area of the read-onlystorage area, the lead-out area of the read-only storage area, and thelead-in area of the writable storage area consecutively, the datatransmission rate and the rotation speed of a spindle motor are varied,thereby slowing down a data recording/reproducing speed. To solve thisproblem, it is preferable for the hybrid disc to store the physicalformat information of the control data zone for the writable storagearea in the lead-in area of the read-only storage area.

For this case, the reserved bytes among 2048 bytes allocated for thephysical format information of the read-only storage area, i.e., thebytes after the 1024^(th) byte, are used to store the physical formatinformation for the writable storage area, and thus the storage ofcorresponding information in the lead-in area of a writable medium canbe omitted. As a result, a delay in writing and reading operations dueto the difference in transmission rate and rotation speed of a spindlemotor can be avoided.

FIG. 10 shows that the control data zone of the lead-in area of theread-only storage area includes physical format information, discmanufacturer information and reserved bytes. The physical formatinformation comprises bytes BP0 to BP2047. BP0 includes the book type(DVD-ROM disc, DVD-RAM disc) and part version. In the present invention,the book type will be “DVD-ROM” so as to be readable by a conventionalDVD-ROM player. BP0 to BP16 includes physical format information for aDVD-ROM, or in this instance, the read-only storage area. BP17 to BP18includes the hybrid disc identification information as shown in FIG. 11.BP19 to BP1023 are reserved bytes. BP1024 to BP2047 are physical formatinformation for a DVD-RAM, or in this instance, the writable storagearea.

As shown in FIG. 12A, a DVD-RAM, which has a writable format, has thesame information structure of an embossed data zone having pits in thelead-in area as that of a DVD-ROM shown in FIG. 12B. In other words, areference code, a buffer zone, an initial zone and the like are the samein terms of size and data value between the two information structures.The only difference between the two information structures lies in thata portion of information of the control data zone is different. Thisminor difference means that the two lead-in areas can be integrated withthe identical information.

If the information of the two lead-in areas is integrated into thelead-in information for the read-only storage region, it is sufficientfor the lead-in area of the writable storage area to only include aconnection zone for connecting the read-only storage area and thewritable storage area, defect management zones DMA 1 and DMA 2, and adrive test zone.

The rewritable lead-in area is located in the writable storage area, andthe connection zone is a mirror zone formed of a reflective layerwithout including any information, which is effective in minimizing theunnecessary space between the read-only storage area and the writablestorage area.

FIG. 13 is a block diagram of an apparatus for recording/reproducinginformation onto/from the optical recording medium according to theembodiments of the present invention.

For a writing operation, an AV CODEC and/or host interface 210compresses an A/V signal from the outside according to a predeterminedcompression scheme, and outputs information on the size of thecompressed AN data. A digital signal processor (DSP) 220 receives thecompressed AN data from the AV CODEC and/or host interface 210, addsadditional information to the received compressed A/V data for errorcorrection coding (ECC), and modulates the data according to apredetermined modulation scheme. A radio frequency amplifier (RF AMP)230 converts the data modulated by the DSP 220 into an RF signal. Apickup unit 240 writes the RF signal from the RF AMP 230 onto thewritable storage area of a disc (any of the hybrid discs 40, 60, 70,90,110 and 130 disclosed herein) mounted on a turn table. A servo unit250 receives information required for servo control from a systemcontroller 260, and stably servo controls the disc.

The system controller 260 generates identification information forindicating a hybrid disc having a read-only storage area and a writablestorage area, and controls the apparatus to write the identificationinformation onto the lead-in area of the read-only storage area throughthe DSP 220 and the RF AMP 230.

On the other hand, for a reading operation, the pickup unit 240 picks upthe data, which is in the form of an optical signal, from a hybrid dischaving a read-only storage area and a writable storage area, and outputsan electrical signal. The RF AMP 230 extracts a servo signal for use inservo controlling and the modulated data. The DSP 220 demodulates themodulated data from the RF AMP 230 based on the modulation scheme usedfor the previous modulation, corrects errors through ECC, and removesthe data added for the ECC. The servo unit 250 receives informationrequired for servo controlling from the RF AMP 130 and the systemcontroller 260, and performs servo controlling. The AV CODEC and/or hostinterface 210 decompresses the compressed AN data from the DSP 220 tooutput the original AN signal. The system controller 260 controls theentire system for reading and writing information data from and to thehybrid disc seated on the turn table by user interfacing.

A problem of hybrid discs having a read-only storage area in a DVD-ROMformat and a writable storage area in a DVD-RAM format is that areference linear velocity is different for each area. Especially, achange in reference linear velocity for the writable storage area variesthe recording characteristics, and thus data cannot be recorded on thearea. On the other hand, as can be seen from an existing multiple speedreproducing system for DVD-ROMs, data can be reproduced from theread-only storage area at variable reproduction speeds, without causingany serious problem.

In the apparatus for alternately and repeatedly reproducing or recordingdata from or onto the read-only storage area and the writable storagearea, respectively, it is preferable that the servo unit 250 reproducesthe data from the read-only storage area at the same reference velocityas the reference linear velocity for recording and reproducing the dataat the innermost part of the writable storage area.

As previously described, the present invention provides an opticalrecording medium having composite recording/reproducing characteristics,in which both a read-only storage area in the existing DVD-ROM format,and a writable storage area having the recording/reproducingcharacteristics defined by a DVD-RAM format are present on an opticalrecording medium such as a hybrid disc. In the hybrid disc according tothe embodiments of the present invention, data correction, modificationand addition of data stored in the read-only storage area is possible,using the writable storage area. In addition, the hybrid disc can beefficiently manufactured by various methods according to the presentinvention.

Although a few preferred embodiments of the present invention have beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A method of recording and reproducing data onto/from an opticalrecording medium having a read-only storage area at an inner part of theoptical recording medium and a writeable storage area at an outer partof the optical recording medium, the method comprising: generatingidentification information to indicate that the optical recording mediumis a hybrid disc having the read-only storage area and the writeablestorage area; and recording the generated identification information ina lead-in area of the read-only storage area.
 2. The method according toclaim 1, further comprising: controlling a reference linear velocity forreproducing data in the read-only storage area to be the same as areference linear velocity of data at an innermost part of the writeablestorage area.
 3. The method according to claim 1, further comprising:generating first control information from the identification informationfor both, the read-only and writeable storage areas and generatingsecond control information from the identification information relatingto the writeable storage area; and recording the first controlinformation in the lead-in area of the read-only storage area andrecording the second control information in a lead-in area of thewriteable storage area.
 4. The method according to claim 3, wherein thefirst control information comprises physical format information of theread-only storage area and physical format information of the writeablestorage area, and the second control information comprises a connectionzone to connect the read-only storage area and the writeable storagearea, a defect management zone to manage defects in the writeablestorage area, and a drive test zone.
 5. The method according to claim 4,further comprising: reading the physical format information of theread-only storage area and of the writeable storage area to reproducedata from the read-only storage area and from the writeable storagearea, respectively, and reading the connection zone, defect managementzone and drive test zone to control the data in the writeable storagearea.
 6. The method according to claim 3, wherein the recording of thefirst control information comprises recording the first controlinformation in reserved bytes of physical format information accordingto a digital versatile disc (DVD) specification.
 7. The method accordingto claim 4, wherein the physical format information of the writeablestorage area is stored in bytes 1024 through 2047 of the first controlinformation.
 8. The method according to claim 4, wherein the physicalformat information of the read-only storage area is stored in bytes 0through 16 of the first control information and the hybrid discidentification information is stored in bytes 17 and 18 of the firstcontrol information.
 9. The method according to claim 4, wherein thephysical format information of the read-only storage area comprises:book type information indicating that the optical recording medium iscompatible with a digital versatile disk read-only memory (DVD-ROM)specification; and a part version indicating a version number of theoptical recording medium.
 10. The method according to claim 4, whereinthe physical format information of the read-only storage area comprises:book type information indicating that the optical recording medium iscompatible with a digital versatile disk read-only memory (DVD-ROM)specification; and a part version information indicating a versionnumber of the optical recording medium; wherein the book typeinformation and part version information are stored in byte 0 of thefirst control information.
 11. The method according to claim 1, whereinthe hybrid disc information comprises part version informationindicating a version number of the hybrid disc.
 12. The method accordingto claim 1, wherein the hybrid disc information comprises: existenceinformation indicating that the optical recording medium is a hybriddisc having the read-only storage area and the writeable storage area;and part version information indicating a version number of the hybriddisc, wherein the existence information and the part version informationare stored in bytes 17 and 18 of the physical format information.
 13. Amethod of reproducing data from an optical recording medium having aread-only storage area at an inner part of the optical recording medium,and a writeable storage area at an outer part of the optical recordingmedium, the method comprising: reading identification information from alead-in area of the read-only storage area to indicate that the opticalrecording medium is a hybrid disc having the read-only storage area andthe writeable storage area; and reading data from the read-only andwriteable storage areas based upon the identification information. 14.The method according to claim 13, further comprising reading first andsecond control information from the identification information, andreading the data from the read-only and writeable storage areas basedupon the read first and second control information.
 15. The methodaccording to claim 14, wherein the reading of the identificationinformation comprises reading the first control information fromreserved bytes of physical format information according to a digitalversatile disc (DVD) specification.
 16. The method according to claim13, wherein the identification information comprises informationindicating a presence or absence of the writeable storage area on thehybrid disc, and information on a part version of the hybrid disc. 17.The method according to claim 13, further comprising controlling areference linear velocity for reproducing data in the read-only storagearea to be the same as a reference linear velocity of data at aninnermost part of the writeable storage area.
 18. A method ofreproducing data from an optical recording medium having a read-onlystorage area at an inner part and a writeable storage area at an outerpart of the optical recording medium, the method comprising: reproducingdata from the read-only storage area and the writeable storage area; andcontrolling a reference linear velocity for reproduction of the data inthe read-only storage area to be the same as a reference linear velocityfor recording or reproduction of the data in an innermost part of thewriteable storage area.